Thank you all for taking the trouble, and time to read my post and comment with ideas and suggestions - some helpful more than others. True, assumptions had to be made, the information I provided was brief.
- there was no mound, but an elevated section of the ground which was never intended to be reduced to the same level as the rest of the garden. This section forms about 10% of the garden which is a fairly large garden; the previous owner of the house grew vegetables in this part of the garden. The tenant has levelled off this ground, and beneficiated the top soil for his own use in his commercial pursuits without the courtesy of discussing it with me.
- the tenant's line of work is a handyman which includes landscaping, therefore I hope it is not unreasonable to assume that he is being opportunistic by taking this topsoil, and exporting it to wherever he is working because he saw that there was value in it.
- when ever he has done handy work at the property, I have always asked him to bill me for the work which I have paid for similar to what I would do if I were paying a contractor.
As for the comments by Grandpa above, this community of Members offers help, it doesn't judge. I never claimed to be suited to be a landlord, you might be better suited that's absolutely fine. But there are fine Members here ready to help as you can see from the above comments. Thank you to everyone who has offered a perspective or two.